Mood disorders, also called affective disorders, are present in around 10% of the general population at any given time. Depression, the most commonly occurring mood disorder, is characterized by symptoms such as feelings of sadness or emptiness, reduced interest in activities that used to be enjoyed, sleep disturbances, loss of energy, and/or suicidal thoughts or intentions (Diagnosis and Statistical Manual (DSM), 4th Edition, 1994).
It is estimated that, in the United States, around 20% of individuals will suffer from a mood disorder at some time, and that around 16% will suffer a major depressive disorder at some time (Kessler, et al. Arch Gen Psychiatry, 2005; 62:593-602). In the United States, around 3-4% of individuals suffering from depression commit suicide; a population accounting for around 60% of the suicide rate in the country (Barlow D H. Abnormal psychology: An integrative approach (5th ed.)).
Subjects diagnosed with depression are typically treated with a combination of psychotherapy and antidepressant medication, both of which may take a period of months or years to reduce depressive symptoms in the subject. Antidepressant medications also typically have side effects that can make taking the medication unpleasant.
Accordingly, there is a need for a treatment for mood disorders that is easy to administer to a subject, that results in prompt alleviation of symptoms, and that does not result in side effects to the subject.